Mobile wireless communication devices, such as a cellular telephone or a wireless personal digital assistant, can provide a wide variety of communication services including, for example, voice communication, text messaging, internet browsing, and electronic mail. Mobile wireless communication devices can operate in a wireless communication network of overlapping “cells”, each cell providing a geographic area of wireless signal coverage that extends from a radio network subsystem located within the cell. The radio network subsystem provides an “air interface” through which the mobile wireless communication device can access the wireless communication network. Whether idle or actively connected, a mobile wireless communication device can be associated with a “serving” cell in a wireless communication network and be aware of “neighbor” cells to which the mobile wireless communication device can also associate. The quality of the air interface between the mobile wireless communication device and the radio network subsystem can vary based on the distance between them, which directly affects received signal power, and on interference included in received signals at either end of the air interface. As the mobile wireless communication device moves further away from the radio network subsystem, eventually a neighbor cell can provide an equal or better performing communication link than the current serving cell. The mobile wireless communication device can include a process for determining if and when to switch cells with which it associates. If the mobile wireless communication device is actively connected to the serving cell, then the process of switching to a neighbor cell is known as “handoff.” For a mobile wireless communication device that is associated with a serving cell in an “idle” state, the process of associating with a neighbor cell is known as “cell reselection.”
When a mobile wireless communication device seeks to associate with a wireless communication network, such as after a power on initialization, the mobile wireless communication device can search for cells located in its vicinity. Initially locating and connecting to a serving cell by a mobile wireless communication device can be referred to as “cell selection”. (The terms “cell selection” and “cell reselection” can be used interchangeably herein, and no limitation is intended by the use of one or the other term.) If a cell is located that is deemed suitable to provide a wireless communication link, e.g. when signals received by the mobile wireless communication device from the radio network subsystem located in the cell exceeds certain performance quality metrics, then the mobile wireless communication device can associate with that cell. The mobile wireless communication device can be referred to as being “camped” on a particular “serving” cell in the wireless communication network of cells. While camped on the serving cell, the mobile wireless communication device can listen to messages broadcast from the serving cell's radio network subsystem as well as from other radio network subsystems located in neighbor cells. System information that specifies certain properties of the serving cell and its neighbor cells can be broadcast regularly by the serving cell's radio network subsystem. If the mobile wireless communication device determines that a neighbor cell can provide a higher quality communication link than a current serving cell, then the mobile wireless communication device can disassociate from the current serving cell and associate with the neighbor cell.
Cell reselection and handover can occur between cells that share a common radio access technology (RAT), such as between two cells in a third generation (3G) Universal Mobile Telecommunication System (UMTS) wireless communication network. In certain circumstances, the mobile wireless communication device can perform an inter-RAT handover (or cell reselection), such as from a 3G UMTS network to a second generation (2G) Global System for Mobile Communications (GSM) network. The mobile wireless communication device can be aware of neighbor cells that use the same radio access technology and of other neighbor cells that use a different radio access technology based on the system information broadcast by the serving cell. Information about certain cells, such as home or office based “femto-cells” that have limited coverage area, however, can be not broadcast by the radio network subsystems of the wireless communication network. Thus, using only the neighbor cells broadcast by the serving cell during handover and cell reselection can limit options for reselection by the mobile wireless communication device, even when the mobile wireless communication device has separate knowledge of “non-broadcast” cells not listed in broadcast system information messages. For example, the mobile wireless communication device can be aware of limited coverage “femto-cells” through a discovery process, such as when searching for cells upon initialization or when recovering from an out-of-service (OOS) condition. Information about the femto-cells can be stored locally in the mobile wireless communication device to use during cell reselection and handover. A femto-cell, if available, can provide benefits for both the user of the mobile wireless communication device (high data rates) and the wireless communication network operator (network offloading). Thus a method to expand a cell search and cell reselection to include stored cells in addition to broadcast cells can be desired.